The invention relates to the recovery of gas from subterranean formations in the earth.
Extensive and high volumes of hydrocarbon gases (e.g., methane) trapped within coal seams have been discovered in various parts of the United States. For example, large amounts of trapped methane gas have been discovered in eastern Wyoming (see, for example, “Powder River Basin Coalbed Methane Play Heats Up,” E&P Perspectives, Vol. X, R57, Oct. 22, 1998 (attached herewith). Naturally occurring degradation processes, such as the biodegradation of microorganisms in the coal is believed to cause the generation of the methane gas trapped within the coal seams.
Methods of economic and environmentally sound gas recovery are underway. A major problem encountered is the large amount of aquifers (water) that impedes the ability to recover the gas from bore holes drilled in to the coal seam. Specifically, the in-ground water serves as a barrier to the effective removal of the gas from the bore hole. The water must be removed by a pump or redirected to allow more efficient removal of the gas. Systems of co-generation of power for pumps are being considered for the prime supply of electrical energy for the pumps. That is, the electrical power for operating gas turbines used to drive the pumps could be generated using a portion of the gas removed from the borehole.